Bupropion hydrochloride is a common antidepressant sold in immediate release, modified release, and extended release tablet forms. See U.S. Pat. Nos. 3,819,706 and 3,885,046. As with many pharmaceuticals, the stability of bupropion hydrochloride is affected by a number of factors including formulation microenvironments and storage conditions.
One formulation of bupropion hydrochloride is taught by Ruff et al., U.S. Pat. No. 5,358,970 to prevent or inhibit degradation of bupropion hydrochloride using one of the stabilizers L-cysteine hydrochloride, glycine hydrochloride, malic acid, sodium metabisulfite, citric acid, tartaric acid and L-cystine dihydrochloride. These solid dosage forms were prepared using alcohol granulation technology. However, granulation technology is labor intensive and costly. In addition special procedures are necessary to address safety and environment issues involving the use of alcohol.
Accordingly, stable bupropion hydrochloride formulations prepared by safe, cost effective methods are greatly desired. The present invention provides such stable bupropion hydrochloride formulations.